Method of diffusing pressurized liquid

ABSTRACT

The invention relates to a diffuser for wet processing systems involved in the manufacturing of semiconductor wafers. The diffuser includes a plenum section and a slitted section. Pressurized fluid from the plenum section is forced through the slitted section and across a plurality of wafers mounted in the wet processing system. One advantage is that by “diffusing” pressurized fluid through the slitted section, a generally uniform and/or laminar flow is achieved. Desirably, the diffuser provides a more reliable, and hence more cost-effective, technology for wet processing fabrication of semiconductor wafers.

RELATED APPLICATION(S)

This application is a divisional of U.S. application Ser. No.09/353,742, filed Jul. 14, 1999 now U.S. Pat. No. 6,539,963, theentirety of which is hereby incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to semiconductor manufacturingand, specifically, to a pressurized diffuser in wet processing systems.

2. Background

Semiconductors are used in highly sophisticated equipment, such ascomputers and the like. Semiconductor chips or dies are typically batchfabricated on a silicon wafer. The wafer may contain hundreds of chipsarranged in a matrix. The chips are separated by sawing thesemiconductor wafer into small squares or rectangles. Each chip is thenmounted on an appropriate substrate, contacted and packaged.

During the fabrication of semiconductor wafers, several process stepsinvolve contacting the wafers with fluids. These include, for example,etching and rinsing of the wafers. The wafer surface is treated with theappropriate liquid(s) to create the desired etch pattern or to cleansethe wafer surface from contaminants. This wet processing generallyutilizes a tank or bath in which one or more wafers are present.Typically, liquid flows over the wafer(s) and is either recirculated ordrained.

It can be difficult to provide a uniform flow of liquid in wetprocessing systems. Uneven fluid flow can lead to unreliable results.For example, the etch pattern formed on the wafers may be unpredictable.Also, the wafers may not be thoroughly cleaned, and hence residualcontaminants may remain on the wafer surface. The undesirable effects ofthis uneven fluid flow can be particularly severe as the end productdevices become more miniaturized and complex.

SUMMARY OF THE INVENTION

The invention relates to a diffuser for wet processing systems involvedin the manufacturing of semiconductor wafers. The diffuser includes aplenum section and a slitted section. Pressurized fluid from the plenumsection is forced through the slitted section and across a plurality ofwafers mounted in the wet processing system. One advantage is that by“diffusing” pressurized fluid through the slitted section a generallyuniform and/or laminar flow is achieved. Desirably, the diffuserprovides a more reliable, and hence more cost-effective, technology forwet processing fabrication of semiconductor wafers.

One embodiment of the invention relates to a wet semiconductorprocessing system. The wet semiconductor processing system comprises aplurality of wafers housed therein. The wet semiconductor processingsystem further comprises a diffuser in liquid communication with thewafers. The diffuser comprises a plurality of plenums adapted to receivea supply of fluid. The diffuser further comprises a plate in fluidcommunication with the plurality of plenums. The plate comprises aplurality of slits, whereby the slits provide a generally uniform flowacross the wafers.

Another embodiment relates to a sparger for a wet processing system. Thesparger comprises a surface with a plurality of slits formed therein,whereby fluid flow emanating through the surface is generally uniform.Yet another embodiment relates to a wet processing system. The wetprocessing system comprises a tank that houses a plurality of wafers.The wet processing system further comprises a diffuser positionedgenerally below the wafers. The diffuser comprises a slitted surface.

A further embodiment relates to a semiconductor processing apparatuswhich comprises a tank. The tank holds one or more wafers. Thesemiconductor processing apparatus further comprises a distributorpositioned generally above the wafers wherein the distributor comprisesa slotted plate.

One aspect of the invention relates to a method for diffusing fluidthrough a wafer processing system. The method comprises the acts ofpressurizing fluid and forcing the fluid through a plurality of slits.The fluid emanating through the plurality of slits has a generallyuniform flow pattern.

Another aspect of the invention relates to a method of manufacturing adiffuser for a semiconductor processing system. The method comprises theacts of forming a plurality of plenums in a first plate and forming aplurality of slits in a second plate. The method further comprises theact of attaching the first plate and the second plate so that the firstplate and the second plate are in fluid communication.

Yet another aspect of the invention relates to a method for wetprocessing of wafers. The method comprises the acts of supporting one ormore wafers in a tank and diffusing pressurized fluid through aplurality of slits, whereby a generally laminar flow is provided acrossthe one or more wafers.

Another embodiment relates to a sparger. The sparger comprises a firstsection with a plurality of plenums adapted to receive a supply offluid. The sparger further comprises a second section in communicationwith the first section. The second section includes a generallystaggered slit pattern to pressurize the fluid within the first section.The slit pattern includes a plurality of rows of slits arranged in arepetitive alternating pattern with each row including one or more ofthe slits.

An additional embodiment of the invention relates to a pressurizedliquid diffuser for a wet processing system. The diffuser comprises aplenum plate including five plenums for receiving a supply of liquid.The plenums are generally rectangular in shape and fabricated frompolyvinylidene fluoride (PVDF). The diffuser further comprises a slittedplate in mechanical and fluid communication with the plenum plate. Theslitted plate is configured to pressurize the liquid within the plenumplate. The slitted plate is generally rectangular in shape and includesfifty rows of slits. Each row includes at least three of the slitsarranged and configured to form an alternating slit pattern between atleast two of the rows.

For purposes of summarizing the invention, certain aspects, advantagesand novel features of the invention have been described herein above. Ofcourse, it is to be understood that not necessarily all such advantagesmay be achieved in accordance with any particular embodiment of theinvention. Thus, the invention may be embodied or carried out in amanner that achieves or optimizes one advantage or group of advantagesas taught herein without necessarily achieving other advantages as maybe taught or suggested herein.

All of these embodiments are intended to be within the scope of theinvention herein disclosed. These and other embodiments of the presentinvention will become readily apparent to those skilled in the art fromthe following detailed description of the preferred embodiments havingreference to the attached figures, the invention not being limited toany particular preferred embodiment(s) disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a wet processing system inaccordance with one embodiment;

FIG. 2 is a schematic illustration of a wet processing system inaccordance with another embodiment;

FIG. 3 is a perspective view of the diffuser of FIGS. 1 and 2;

FIG. 4 is an exploded perspective view of the diffuser of FIG. 3;

FIG. 5 is a cross-sectional along line 5—5 of FIG. 3;

FIG. 6 is a side elevational view of the diffuser plenum plate of FIG.3;

FIG. 7 is a top plan view of the diffuser plenum plate of FIG. 3;

FIG. 8 is a side elevational view of the diffuser slitted plate of FIG.3;

FIG. 9 is a top plan view of the diffuser slitted plate of FIG. 3;

FIG. 10 is a side elevational view of one of the manifolds of FIGS. 1and 2; and

FIG. 11 is a top plan view of the manifold of FIG. 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a schematic drawing of a wet semiconductor wafer processingsystem or apparatus 10 in accordance with one embodiment. The wetprocessing system 10 generally comprises an outer tank 12, and an innertank or bath 14 with a lower chamber 16, and an upper chamber 18separated by a fluid diffuser, sparger or distributor 20. The diffuser20 includes a bottom plenum plate 22 and a top slitted plate 24, asdiscussed in greater detail later herein. In one embodiment, one or moremanifolds 26 are in fluid communication with the plenum plate 22. Themanifolds 26 are housed in the lower chamber 16. The skilled artisanwill recognize that the lower chamber 16 can be excluded from the wetprocessing system 10, as required or desired.

The wet processing system 10 typically holds a fluid or liquid 30 andone or more wafers 32. In one embodiment, the wafers 32 reside in theupper chamber 18 of the inner tank 14 and are submerged in the fluid 30.A wafer carrier 34, residing in the upper chamber 18, is utilized tosupport the wafers 32. The wafer carrier 34 assists in aligning thewafers 32 with respect to the diffuser 20. In another embodiment, thewafers 32 may be supported directly in the inner tank 14 by suitablesupporting rods (not shown).

The wafers 32 are held in a stationary position within the wetprocessing system 10. In one embodiment, the wafer carrier 34 positionsthe wafers 32 with their large flat sides 35 vertically oriented andspaced in generally parallel aligned relation. The wafer carrier 34supports fifty wafers 32. The skilled artisan will recognize that thewet processing system 10 can be used in conjunction with fewer or morewafers 32.

With the inner tank 14 generally filled with fluid 30, a flow of fluid30 is also provided to the inner tank 14 via an inlet feed line 36connected to the manifolds 26. The fluid 30 flows through the manifolds26, the plenum plate 22, the slitted plate 24 and in a generally upwarddirection over the wafers 32. As discussed in detail below, the diffuser20 provides for a generally uniform and/or laminar flow pattern 38 overthe wafers 32. The fluid 30 then flows over the upper rim 40 of theinner tank 14 and into the outer tank 12.

In one embodiment, a heating station 27 is provided upstream of thediffuser 20. The heating station 27 houses one or more heating elementsor heaters 28. One or more of the heating elements 28 may be operated tocontrol the temperature of the fluid 30, as required or desired. Inother embodiments, a wide variety of other suitable fluid heating meanscan be used to heat the fluid 30 upstream or downstream of the diffuser20, as required or desired.

In one embodiment, a pump 42 supplies fluid 30 from a reservoir orsource 44 to the wet processing system 10 via the inlet feed line 36. Inanother embodiment, a pressurized facility supply line 46 provides fluid30 to the wet processing system 10 via the inlet feed line 36. The fluid30 exits the wet processing system 10 via an outlet feed line 48. Theexiting fluid 30 is recirculated back into the wet processing system 10using, for example, the pump 42. The exiting fluid 30 is transported toa drain or reservoir 50. Various shut-off valves 52 may be used todirect the flow of fluid 30 to and from the wet processing system 10, asrequired or desired. The skilled artisan will readily comprehend theoperation of such valves 52.

The pump 42 can be a wide variety of commercially available pumps. Inone embodiment, the pump 42 is an Air Drive Bellows, available fromIwaki. The skilled artisan will recognize that other types of pumps maybe utilized with efficacy. In one embodiment, the pump 42 provides aflow rate of about 20 liters/min at a pressure of about 207 kilopascals(30 psi). In other embodiments, as the skilled artisan will recognize, awide variety of operating flow rates and operating pressures can be usedwith efficacy, as required or desired.

The wet processing system 10 can be used in conjunction with a widevariety of steps involved in the fabrication of semiconductor wafers.These include, for example, etching, cleaning and rinsing of the wafers32. The fluid 30 may comprise a wide variety of liquids. These liquidsinclude, but are not limited to, deionized (DI) water, dilutehydrofluoric acid (DHF), “Piranha” (a solution typically comprising ofsulfuric acid and hydrogen peroxide), sulfuric acid, phosphoric acid,nitric acid, hydrochloric acid, ammonium hydroxide, hydrogen peroxide,and isopropyl alcohol, among others. The skilled artisan will recognizethat, in general, the wet processing system 10 can be used for anyprocessing step in which a fluid flows across the wafers 32.

The outer tank 12 has a depth of about 33 cm, a width of about 33 cm,and a length of about 50 cm. The inner tank 14 has a depth of about 27cm, a width of about 25 cm, and a length of about 42 cm. The lowerchamber 16 has a depth of about 9 cm, a width of about 25 cm, and alength of about 42 cm. The upper chamber 18 has a depth of about 24 cm,a width of about 25 cm, and a length of about 42 cm. The inlet feed line36 has an internal diameter of about 2 cm and the outlet feed line 48has an internal diameter of about 2 cm. In other embodiments, as theskilled artisan will recognize, the outer tank 12, the inner tank 14,the lower chamber 16, the upper chamber 18, the inlet feed line 36, andthe outlet feed line 48 may be dimensioned and configured in a widevariety of manners, as required or desired.

The outer tank 12, the inner tank 14, the lower chamber 16, the upperchamber 18, the inlet feed line 36, and the outlet feed line 48 may befabricated from a wide variety of materials with efficacy, as is knownin the art. The skilled artisan will recognize that the heating elements28 can be a wide variety of commercially available fluid heaters.

The wet processing system 10 can be used in conjunction with a widevariety of wafers 32. In one embodiment, the wafers 32 comprise silicon.In other embodiments, the wafers 32 may comprise other semiconductormaterials, as required or desired. The wafers 32 have a thickness ofabout 725 microns (μm) and a diameter of about 20 cm. In otherembodiments, the skilled artisan will recognize that the wafers 32 maybe dimensioned and configured in a wide variety of manners, as requiredor desired.

The wafer carrier 34 can be one of a wide variety of wafer carriers asare known in the art. In one embodiment, a wafer carrier 34 as disclosedin U.S. Pat. No. 5,788,304, incorporated herein by reference, isutilized. In other embodiments, the skilled artisan will recognize thatother wafer carriers may be used, as required or desired, giving dueconsideration to the goal of providing support to the wafers 32.

FIG. 2 is a schematic drawing of a wet semiconductor wafer processingsystem or apparatus 110 in accordance with one embodiment. The wetprocessing system 110 generally comprises a tank or bath 13 with achamber 17, and a fluid diffuser, sparger or distributor 20 at the topend of the tank 13. The diffuser 20 includes a top plenum plate 22 and abottom slitted plate 24, as discussed in greater detail later herein. Inone embodiment, one or more manifolds 26 are in fluid communication withthe plenum plate 22. The tank 13 can also include an additional upperchamber for housing the manifolds 26. In one embodiment, an outer tankwith a lid can house the tank 13 and the diffuser 20 can be mounted onthe outer tank lid.

The wet processing system 10 typically holds a fluid or liquid 30 andone or more wafers 32. In one embodiment, the wafers 32 reside in thechamber 17 of the tank 13 and are substantially adjacent to the diffuser20 so that the fluid level 31 in the chamber 17 is below the wafers 32.A wafer carrier 34, residing in the chamber 17, is utilized to supportthe wafers 32. The wafer carrier 34 assists in aligning the wafers 32with respect to the diffuser 20. In another embodiment, the wafers 32may be supported directly in the tank 13 by suitable supporting rods(not shown).

The wafers 32 are held in a stationary position within the wetprocessing system 110. In one embodiment, the wafer carrier 34 positionsthe wafers 32 with their large flat sides 35 vertically oriented andspaced in generally parallel aligned relation. The skilled artisan willrecognize that the wet processing system 110 can be used in conjunctionwith fewer or more wafers 32.

A flow of fluid 30 is provided to the tank 13 via an inlet feed line 36connected to the manifolds 26. The fluid 30 flows through the manifolds26, the plenum plate 22, the slitted plate 24 and in a generallydownward direction over the wafers 32. As discussed in detail below, thediffuser 20 provides for a generally uniform and/or laminar flow pattern138 over the wafers 32, and operates akin to a “showerhead.” Asindicated above, the fluid level 31 in the chamber 17 is below thewafers 32 so that the chamber 17 is partially devoid of fluid 30.

In one embodiment, a heating station 27 is provided upstream of thediffuser 20. The heating station 27 houses one or more heating elementsor heaters 28. One or more of the heating elements 28 may be operated tocontrol the temperature of the fluid 30, as required or desired. Inother embodiments, a wide variety of other suitable fluid heating meanscan be used to heat the fluid 30 upstream or downstream of the diffuser20, as required or desired.

In one embodiment, a pump 42 supplies fluid 30 from a reservoir orsource 44 to the wet processing system 110 via the inlet feed line 36.In another embodiment, a pressurized facility supply line 46 providesfluid 30 to the wet processing system 110 via the inlet feed line 36.The fluid 30 exits the wet processing system 110 via an outlet feed line48. The exiting fluid 30 is recirculated back into the wet processingsystem 110 using, for example, the pump 42, and the exiting fluid 30 istransported to a drain or reservoir 50. Various shut-off valves 52 maybe used to direct the flow of fluid 30 to and from the wet processingsystem 110, as required or desired. The skilled artisan will readilycomprehend the operation of such valves 52.

Diffuser

FIGS. 3 to 5 illustrate the diffuser, sparger or distributor 20 of FIGS.1 and 2. As indicated above, the diffuser 20 comprises a first plenumplate or section 22 and a second slitted plate, section or surface 24.The plenum plate 22 and the slitted plate 24 are in mechanicalcommunication with one another and are substantially aligned with oneanother, as discussed in further detail below. The diffuser 20 isadapted to be mounted in the wet processing system 10 (FIG. 1) and/orthe wet processing system 110 (FIG. 2).

The diffuser 20 is fabricated from polyvinylidene fluoride (PVDF). Inanother embodiment, the diffuser 20 is fabricated from quartz. In otherembodiments, the skilled artisan will recognize that the diffuser 20 canbe fabricated from a wide variety of other suitable materials, withefficacy.

In one embodiment, the plenum plate 22 and the slitted plate 24 aremanufactured separately, and then attached to one another to form thediffuser 20. For example, the plenum plate 22 and the slitted plate 24may be formed by machining or laser cutting and then attached byutilizing welding or bonding. In another embodiment, the diffuser 20,comprising the plenum plate 22 and the slitted plate 24, may bemanufactured as a unitary element. In other embodiments, the diffuser 20can be fabricated by a variety of other methods, for example, molding,casting, and forging, among others.

Referring in particular to FIG. 3, in one embodiment, the diffuser 20has a height (H) of about 2.54 cm (1.00 inches), a width (W) of about24.77 cm (9.75 inches), and a length (L) of about 31.59 cm (12.44inches). In another embodiment, the diffuser 20 has a height (H) in therange from about 1 cm to 25 cm, a width (W) in the range from about 10cm to 40 cm, and a length (L) in the range from about 1 cm to 50 cm. Inother embodiments, the skilled artisan will recognize that the diffuser20 may be dimensioned and configured in a wide variety of manners, asrequired or desired.

Plenum Plate

Referring in particular to FIGS. 3 to 7, the plenum plate 22 includes aplurality of plenums, chambers or receptacles 54. In one embodiment, theplenum plate 22 includes five plenums 54. In other embodiments, theplenum plate 22 may include fewer or more plenums 54, as required ordesired. The plenums 54 are generally rectangular in shape, though theskilled artisan will readily recognize that other shapes may be utilizedwith efficacy. In one embodiment, the plenum plate 22 includes crosswalls 56, end walls 58, and side walls 60 in communication with a baseplate or section 62 to define the plenums 54.

The base section 62 of the plenum plate 22 includes a plurality ofopenings 64. In one embodiment, the openings 64 are positionedsubstantially adjacent to the side walls 60. As discussed in greaterdetail later herein, the openings 64 interface with the manifolds 26(FIGS. 1 and 2). In one embodiment, the base section 62 includes tenopenings 64 with two openings 64 being associated with each one of fiveplenums 54 to form two groups 66 of openings 64. In other embodiments,as the skilled artisan will recognize, the base section 62 may includefewer or more openings 64, and the distribution and positioning of theopenings 64 among the plenums 54 may be varied, as required or desired.

In one embodiment, the plenum plate 22 is fabricated from polyvinylidenefluoride (PVDF). In another embodiment, the plenum plate 22 isfabricated from quartz. In other embodiments, the skilled artisan willrecognize that the plenum plate 22 can be fabricated from a wide varietyof other suitable materials, with efficacy.

The plenum plate 22 is fabricated by machining. In another embodiment,the plenum plate 22 is fabricated by laser cutting. In otherembodiments, as the skilled artisan will recognize, the plenum plate 22can be fabricated by a wide variety of other methods, for example,molding, casting and forging, among others. Also, one or more of theplenums 54 may be fabricated separately, and then combined with one ormore plenums 54 to form the plenum plate 22.

Referring in particular to FIG. 4, in one embodiment, the plenum plate22 has a height (H_(pp)) of about 1.91 cm (0.75 inches), a width(W_(pp)) of about 24.77 cm (9.75 inches), and a length (L_(pp)) of about31.59 cm (12.44 inches). In other embodiments, the skilled artisan willrecognize that the plenum plate 22 may be dimensioned and configured ina wide variety of manners, as required or desired.

The plenums 54 have a height of about 1.588 cm (0.625 inches), a widthof about 23.81 cm (9.375 inches), and a length of about 5.842 cm (2.30inches). The cross walls 56 have a thickness of about 0.4763 cm (0.1875inches). The end walls 58 have a thickness of about 0.2381 cm (0.09375inches). The side walls 60 have a thickness of about 0.4763 cm (0.1875inches). The base plate 62 has a thickness of about 0.3175 cm (0.125inches). The openings 64 have a diameter of about 1.27 cm (0.5 inches).Neighboring openings 64 of an opening group 66 are spaced by a distance(D1), labeled in FIG. 7, of about 5.874 cm (2.313 inches) from oneanother. The openings 64 associated with the same plenum 54 are spacedby a distance (D2), labeled in FIG. 7, of about 23 cm from one another.In other embodiments, the skilled artisan will recognize that theplenums 54, the cross walls 56, the end walls 58, the side walls 60, thebase plate 62, and the openings 64 may be dimensioned and configured ina wide variety of manners, as required or desired.

Slitted Plate

Referring in particular to FIGS. 3 to 5 and 8 to 9, the slitted orslotted plate 24 includes a plurality of slits or slots 68. In oneembodiment, the slitted plate 24 has side rails 70 and end edges 71which border the slits 68. In one embodiment, the slitted plate 24 isgenerally rectangular in shape, though as the skilled artisan willrecognize, other shapes may be utilized with efficacy, as required ordesired.

The slitted plate 24 includes a staggered pattern 72 of slits 68. Theslitted plate 24 includes a plurality of rows 74 of slits 68. In oneembodiment, the rows 74 are spaced such that an individual one of thewafers 32 (FIGS. 1 and 2) can be positioned near a respective row 74without blocking the slits 68 in adjacent rows 74. The rows 74 are alsospaced such that they provide enough spacing between adjacent wafers 32.Thus, the wafers 32 have a generally insignificant effect on the flowpattern across neighboring wafers 32.

In one embodiment, the slitted plate 24 includes fifty rows 74 of slits68 which can be used in conjunction with up to fifty wafers 32 (FIGS. 1and 2). In other embodiments, as the skilled artisan will recognize, theslitted plate 24 can include fewer or more rows 74 of slits 68, asrequired or desired. Each row 74 of slits 68 includes three slits 68. Inother embodiments, as the skilled artisan will recognize, the slittedplate 24 can include fewer or more slits 68 in each row 74, as requiredor desired, based on providing generally uniform and/or laminar flow andpreserving the structural integrity of the slitted plate 24.

The slits 68 are dimensioned, configured and patterned to pressurize thefluid 30 within the plenum plate 22 to a selected pressure value orrange. Thus, as fluid 30 is forced through the slits 68 it emanates in agenerally uniform and/or laminar flow pattern 38 (FIG. 1), 138 (FIG. 2).In other embodiments, the slits 68 may be dimensioned and configured ina wide variety of ways, as required or desired, giving due considerationto the goal of providing generally uniform and/or laminar flow.

The slit pattern 72 includes a repetitive alternating pattern of rows74. This is illustrated by referring to FIG. 9 which shows rows 74 a and74 b. In one embodiment, rows 74 a include three slits 68 with a shortercentral slit 68 a between two longer end slits 68 b. The rows 74 binclude three slits 68 with a longer central slit 68 a′ between twoshorter end slits 68 b′. The row 74 a is neighbored by row(s) 74 b andoccurs alternately in the slit pattern 72. The row 74 b is neighbored byrow(s) 74 a and occurs alternately in the slit pattern 72.

In one embodiment, the slitted plate 24 is fabricated frompolyvinylidene fluoride (PVDF). In another embodiment, the slitted plate24 is fabricated from quartz. In other embodiments, the skilled artisanwill recognize that the slitted plate 24 can be fabricated from a widevariety of other suitable materials, with efficacy.

The slitted plate 24 is fabricated by machining. In another embodiment,the slitted plate 24 is fabricated by laser cutting. In otherembodiments, as the skilled artisan will recognize, the slitted plate 24can be fabricated by a wide variety of other methods, for example,molding, casting and forging, among others. Also, the slitted plate 24may be fabricated in sections which can then be combined to form theslitted plate 24.

In one embodiment, the slitted plate 24 has a height (H_(sp)) of about0.635 cm (0.25 inches), a width (W_(sp)) of about 24.77 cm (9.75inches), and a length (L_(sp)) of about 31.59 cm (12.44 inches). Inother embodiments, the skilled artisan will recognize that the slittedplate 24 may be dimensioned and configured in a wide variety of manners,as required or desired. As indicated above, the slitted plate 24 isdimensioned, configured and patterned with slits 68 to pressurize thefluid 30 within the plenum plate 22 to a selected pressure value orrange. Thus, as fluid 30 is forced through the slits 68 it emanates in agenerally uniform and/or laminar flow pattern 38 (FIG. 1), 138 (FIG. 2).In other embodiments, the slitted plate 24 may be dimensioned andconfigured in a wide variety of ways, as required or desired, giving dueconsideration to the goal of providing generally uniform and/or laminarflow.

The side rails 70 have a height of about 0.635 cm (0.25 inches), a widthof about 2.204 cm (0.8676 inches), and a length of about 31.59 cm (12.44inches). The end edges 71 are spaced from the center of respectiveadjacent slits 68 by a distance of about 0.2819 cm (0.111 inches). Inother embodiments, the skilled artisan will recognize that the siderails 70 and end edges 71 may be dimensioned and spaced in a widevariety of manners, as required or desired.

The center-to-center spacing between adjacent slit rows 74 is about0.635 cm (0.25 inches). As indicated above, the rows 74 are spaced suchthat an individual one of the wafers 32 (FIGS. 1 and 2) can bepositioned near a respective row 74 without blocking the slits 68 inadjacent rows 74. The rows 74 are also spaced such that they provideenough spacing between adjacent wafers 32. Thus, the wafers 32 have agenerally insignificant effect on the flow pattern across neighboringwafers 32. In other embodiments, the skilled artisan will recognize thatthe spacing between the rows 74 may be varied in a wide variety ofmanners, as required or desired.

The slits 68 have a depth of about 0.635 cm (0.25 inches). The slits 68have a width in the range from about 0.0508 cm (0.02 inches) to 0.0762cm (0.03 inches). The slits 68 have a length in the range from about4.763 cm (1.875 inches) to 10.16 cm (4.0 inches). In other embodiments,the skilled artisan will recognize that the slits 68 may be dimensionedand configured in a wide variety of manners, as required or desired.

The spacing between adjacent slits 68 in a row 74, for example, adjacentslits 68 a and 68 b in row 74 a, is about 0.3175 cm (0.125 inches).Similarly, in one embodiment, the spacing between adjacent slits 68 in arow 74, for example, adjacent slits 68 a′ and 68 b′ in row 74 b, isabout 0.3175 cm (0.125 inches). In other embodiments, the skilledartisan will recognize that the slits 68 may be dimensioned andconfigured in a wide variety of manners, as required or desired.

The slits 68 a of rows 74 a have a length of about 4.763 cm (1.875inches) and slits 68 b of rows 74 a have a length of about 7.461 cm(2.938 inches). In one embodiment, slits 68 a′ of rows 74 b have alength of about 10.16 cm (4.0 inches) and slits 68 b′ of rows 74 b havea length of about 4.763 cm (1.875 inches). In other embodiments, theskilled artisan will recognize that the slits 68 and rows 74 may bedimensioned and configured in a wide variety of manners, as required ordesired.

Referring in particular to FIGS. 4 and 9, in one embodiment, ten rows 74of slits 68 are in fluid communication with each plenum 54 of the plenumplate 22. In other embodiments, fewer or more rows 74 can be in fluidcommunication with each plenum 54, as required or desired, giving dueconsideration to the goals of providing generally uniform and/or laminarflow.

Manifolds

FIGS. 10 and 11 illustrate one of the manifolds 26 of FIGS. 1 and 2 inaccordance with one embodiment. In one embodiment, the wet processingsystem 10 (FIG. 1) includes two manifolds 26. In other embodiments, thewet processing system 10 (FIG. 1) may include fewer or more manifolds26, as required or desired, giving due consideration to the goals ofproviding generally uniform and/or laminar flow. In one embodiment, thewet processing system 110 (FIG. 2) includes two manifolds 26. In otherembodiments, the wet processing system 110 (FIG. 2) may include fewer ormore manifolds 26, as required or desired, giving due consideration tothe goals of providing generally uniform and/or laminar flow.

The manifold 26 generally comprises a main supply rail 76 in fluidcommunication with a plurality of channels 78. In one embodiment, themanifold 26 includes five channels 78. In other embodiments, themanifold 26 can include fewer or more channels 78, as required ordesired, giving due consideration to the goals of providing generallyuniform and/or laminar flow.

A threaded opening 80 at one end of the manifold supply rail 76 permitsfluid 30 to be fed into the manifold channels 78 from the inlet feedline 36 (FIGS. 1 and 2) utilizing suitable tubing and fittings. In otherembodiments, the opening 80 may be located at other suitable positionson the manifold supply rail 76, as required or desired. In oneembodiment, steps 82 are provided in the manifold 26 to generally definea first portion 84 and a second portion 86. The manifold first portion84 generally includes the supply rail 76 and the manifold second portion86 generally includes the channels 78.

The projections 88 are provided at the ends of the channels 78. Theseprojections 88 are spaced, sized and configured to mate with the plenumplate openings 64 (shown, for example, in FIGS. 4 and 7). In oneembodiment, the manifold projections 88 are attached to the plenum plateopenings 64 by using welding or bonding. Also, the manifolds 26 arecoupled to the plenum plate 22 by utilizing welding or bonding. In otherembodiments, as the skilled artisan will recognize, the manifold 26 maybe coupled to the plenum plate 22 by a wide variety of means, forexample, by using suitable connectors and the like.

The skilled artisan will recognize that the manifold(s) 26 may befabricated using a wide variety of materials, as required or desired.The manifold(s) 26 may be manufactured by utilizing a wide variety ofmanufacturing techniques with efficacy, as will be recognized by thoseskilled in the art.

Referring to FIGS. 10 and 11, in one embodiment, the manifold 26 has aheight (H_(m)) of about 3.81 cm (1.5 inches), a width (W_(m)) of about1.905 cm (0.75 inches), and a length (L_(m)) of about 36.67 cm (14.44inches). In other embodiments, the skilled artisan will recognize thatthe manifold 26 may be dimensioned and configured in a wide variety ofmanners, as required or desired.

The supply rail 76 has a diameter of about 1.429 cm (0.5625 inches) anda length of about 30.56 cm (12.03 inches). The channels 78 have adiameter of about 0.9525 cm (0.375 inches). The spacing between adjacentchannels 78 is about 5.874 cm (2.313 inches). The spacing between theoutermost channels 78 and the lengthwise ends of the manifold 26 isabout 6.588 cm (2.594 inches). The projections 88 have a diameter ofabout 0.9525 cm (0.375 inches), an outer diameter of about 1.27 cm (0.5inches) and a length of about 0.3175 cm (0.125 inches). The spacingbetween adjacent projections 88 is about 5.874 cm (2.313 inches). Thespacing between the outermost projections 88 and the lengthwise ends ofthe manifold 26 is about 6.588 cm (2.594 inches).

The manifold first portion 84 has a height of about 2.223 cm (0.875inches), a width of about 1.905 cm (0.75 inches), and a length of about36.67 cm (14.44 inches). The manifold second portion 86 has a height ofabout 1.588 cm (0.625 inches), a width of about 1.905 cm (0.75 inches),and a length of about 30.32 cm (11.94 inches). In other embodiments, theskilled artisan will recognize that the supply rail 76, the channels 78,projections 88, the manifold first portion 84, and the manifold secondportion 86 may be dimensioned and configured in a wide variety ofmanners, as required or desired.

Diffuser Assembly Process

The process of forming the diffuser 20 includes providing the plenumplate 22 and the slitted plate 24. The cross walls 56, the end walls 58,the side walls 60 and the base plate 62 are created to form the plenums54. A plurality of openings 64 are created in the base plate 62 to formthe plenum plate 22.

The plenum plate 22 is fabricated by machining a sheet of material. Inanother embodiment, the plenum plate 22 is fabricated by laser cutting.In other embodiments, as the skilled artisan will recognize, the plenumplate 22 can be fabricated by a wide variety of other methods, forexample, molding, casting and forging, among others.

A plurality of slits 68 flanked by side rails 70 is created to form theslitted plate 24. The slits 68 are arranged in a staggered pattern 72.In one embodiment, the staggered pattern 72 includes a plurality of rows74 of slits 68. In one embodiment, each row 74 of slits 68 includes aplurality of slits 68.

The slitted plate 24 is fabricated by machining a sheet of material. Inanother embodiment, the slitted plate 24 is fabricated by laser cutting.In other embodiments, as the skilled artisan will recognize, the slittedplate 24 can be fabricated by a wide variety of other methods, forexample, molding, casting and forging, among others.

The plenum plate 22 and the slitted plate 24 are attached so that theyare aligned with one another, and in mechanical and fluid communicationwith one another to form the diffuser 20. The plenum plate 22 and theslitted plate 24 are attached by utilizing welding or bonding. In oneembodiment, each plenum 54 is in fluid communication with ten rows 74 ofslits 68.

In one embodiment, the diffuser 20 is mounted in the wet processingsystem 10 (FIG. 1) to provide generally uniform and/or laminar flowacross the wafers 32. In another embodiment, the diffuser 20 is mountedin the wet processing system 110 (FIG. 2) to provide generally uniformand/or laminar flow across the wafers 32.

Operation

In one embodiment, and referring to FIG. 1, the pressurized liquiddiffuser 20 provides a generally uniform and/or laminar flow 38 over thewafers 32 in the wet processing system 10. As indicated above, the fluid30 enters the inner tank 14 via inlet feed line 36. The fluid 30 thenflows through the manifolds 26, the plenum plate 22, the slitted plate24 and in a generally upwards direction over the wafers 32. The fluid 30flows over the upper rim 40 of the inner tank 14 and into the outer tank12. The fluid 30 exits the wet processing system 10 via the outlet feedline 48. In one embodiment, each row 74 of slits 68 is associated with arespective one of the wafers 32, to provide fluid 30 for waferprocessing.

Referring to FIG. 1, the generally uniform and/or laminar flow 38 overthe wafers 32 is achieved, at least partially, due to the pressurizingof the fluid 30 within the plenum plate 22, and hence the generation ofsubstantially large local pressure drops through the slitted plate 24.Pressurized fluid 30 from the plenum plate 22 is forced through theslitted plate 24, and emanates in a generally uniform and/or laminarflow 38. In one embodiment, the slits 68 (see, for example, FIG. 9) ofthe slitted plate 24 are configured such that the open area provided bythe slits 68 is approximately equal to the inlet flow area provided bythe inlet feed line 36. Thus, a balance is achieved between the inletaverage velocity through the inlet feed line 36 and the average velocitythrough the slitted plate 24 (or diffuser 20). In other embodiments, theinlet average velocity through the inlet feed line 36 can be less ormore than the average velocity through the slitted plate 24 (or diffuser20), as required or desired, giving due consideration to the goals ofproviding generally uniform and/or laminar flow.

In another embodiment, and referring to FIG. 2, the pressurized liquiddiffuser 20 provides a generally uniform and/or laminar flow 138 overthe wafers 32 in the wet processing system 110. As indicated above,fluid 30 from the inlet feed line 36 enters the manifolds 26. The fluid30 then flows through the plenum plate 22, the slitted plate 24 and in agenerally downwards direction over the wafers 32. The fluid 30 exits thewet processing system 110 via the outlet feed line 48. In oneembodiment, each row 74 of slits 68 is associated with a respective oneof the wafers 32, to provide fluid 30 for wafer processing.

Referring to FIG. 2, the generally uniform and/or laminar flow 138 overthe wafers 32 is achieved, at least partially, due to the pressurizingof the fluid 30 within the plenum plate 22, and hence the generation ofsubstantially large local pressure drops through the slitted plate 24.Pressurized fluid 30 from the plenum plate 22 is forced through theslitted plate 24, and emanates in a generally uniform and/or laminarflow 38. In one embodiment, the slits 68 (see, for example, FIG. 9) ofthe slitted plate 24 are configured such that the open area provided bythe slits 68 is approximately equal to the inlet flow area provided bythe inlet feed line 36. Thus, a balance is achieved between the inletaverage velocity through the inlet feed line 36 and the average velocitythrough the slitted plate 24 (or diffuser 20). In other embodiments, theinlet average velocity through the inlet feed line 36 can be less ormore than the average velocity through the slitted plate 24 (or diffuser20), as required or desired, giving due consideration to the goals ofproviding generally uniform and/or laminar flow.

The pressurized liquid diffuser 20 (see, for example, FIG. 4)demonstrates certain advantages over conventional wet processing ofwafers. One advantage is that by “diffusing” the fluid 30 (FIGS. 1 and2) through the slits 68 a generally uniform and/or laminar flow isprovided across the wafers 32 and the system tank, such as the innertank 14 (FIG. 1) and the tank 13 (FIG. 2). Desirably, this results inmore reliable and repeatable wet processing of wafers 32, for example,by providing improved, cleaner etches and rinses. Additionally, thefluid 30 contacts much or all the active wafer surface (FIGS. 1 and 2)generally evenly.

While the components and techniques of the present invention have beendescribed with a certain degree of particularity, it is manifest thatmany changes may be made in the specific designs, constructions andmethodology hereinabove described without departing from the spirit andscope of this disclosure. It should be understood that the invention isnot limited to the embodiments set forth herein for purposes ofexemplification, but is to be defined only by a fair reading of theappended claims, including the full range of equivalency to which eachelement thereof is entitled.

What is claimed is:
 1. A method for diffusing fluid through a waferprocessing system, comprising: pressurizing fluid; and forcing the fluidthrough a plate having a plurality of slits arranged in rows with aplurality of the rows having at least one central slit, the centralslits of at least two rows having different lengths.
 2. The method ofclaim 1, wherein the act of forcing the fluid, forces fluid through twoadjacent rows with central slits of different lengths.
 3. The method ofclaim 2, wherein the act of pressurizing fluid comprises the act ofpressurizing fluid in a plurality of plenums in fluid communication withthe plate.
 4. The method of claim 1, wherein the act of forcing thefluid improves the uniformity of the flow pattern.
 5. The method ofclaim 4, wherein the act of pressurizing fluid comprises the act ofpressurizing fluid in five plenums in fluid communication with theplate.
 6. The method of claim 1, wherein the act of pressurizing fluidcomprises the act of pressurizing fluid in at least one plenum in fluidcommunication with the plate.
 7. The method of claim 1, wherein the actof forcing the fluid comprises the act of generating substantially largelocal pressure drops through the slits.
 8. The method of claim 1,wherein the method further comprises the act of supplying fluid to theplate through a manifold.
 9. A method for wet processing of wafers,comprising: supporting one or more wafers in a tank; and diffusingpressurized fluid through a plate having a plurality of slits arrangedin rows with a plurality of the rows having at least one central slit,the central slits of at least two rows having different lengths, wherebythe fluid flows across the one or more wafers.
 10. The method of claim9, wherein the act of diffusing pressurized fluid forces fluid throughadjacent rows with central slits of different lengths.
 11. The method ofclaim 9, wherein the act of diffusing pressured fluid through the plategenerates a generally laminar flow across the one or more wafers. 12.The method of claim 9, wherein the act of supporting one or more waferscomprises the act of supporting one or more wafers in a wafer carrier.13. The method of claim 9, wherein the act of supporting one or morewafers comprises the act of supporting one or more wafers substantiallystationarily.
 14. The method of claim 9, wherein the act of supportingone or more wafers comprises the act of positioning the wafers withtheir flat sides vertically oriented and spaced in generally parallelaligned relation.
 15. The method of claim 9, wherein the act ofsupporting one or more wafers comprises the act of supporting fiftywafers.
 16. The method of claim 9, wherein the act of diffusingpressurized fluid comprises the act of forcing the fluid through theslits in to the tank.
 17. A method for diffusing fluid through a waferprocessing system, comprising: pressurizing fluid; and forcing the fluidthrough a plate having a plurality of slits arranged in rows with aplurality of the rows having at least one end slit wherein at least twoof the rows have end slits of different lengths.
 18. The method of claim17, wherein the act of forcing the fluid, forces the fluid throughadjacent rows with end slits of different lengths.
 19. The method ofclaim 17, wherein the act of forcing the fluid generates a generallyuniform flow pattern.
 20. The method of claim 17, wherein the act offorcing the fluid comprises the act of forcing the fluid through aplurality of the slits arranged in a staggered pattern.
 21. The methodof claim 17, wherein the act of forcing the fluid comprises the act offorcing the fluid through a plurality of the rows arranged in arepetitive alternating pattern.
 22. The method of claim 17, wherein theact of forcing the fluid comprises the act of forcing the fluid throughat least one row having a slit pattern comprising a longer central slitbetween two shorter end slits.
 23. The method of claim 17, wherein theact of forcing the fluid comprises the act of forcing the fluid throughat least one row having a slit pattern comprising a shorter central slitbetween two longer end slits.
 24. The method of claim 17, wherein theact of forcing the fluid comprises the act of forcing the fluid througha plurality of the rows which form a pattern with rows having a shortercentral slit between two longer end slits being neighbored by rowshaving a longer central slit between two shorter end slits.
 25. A methodfor wet processing of wafers, comprising: supporting one or more wafersin a tank; and diffusing pressurized fluid through a plate having aplurality of slits arranged in rows with a plurality of the rows havingat least one end slit, wherein at least two rows have end slits ofdifferent lengths.
 26. The method of claim 25, wherein the act ofdiffusing pressurized fluid, forces fluid through two adjacent rows withend slits of different lengths.
 27. The method of claim 25, wherein theact of diffusing pressurized fluid improves the laminar flow across theone or more wafers.
 28. The method of claim 25, wherein the act ofsupporting one or more wafers comprises the act of positioning thewafers substantially parallel to the slits.
 29. The method of claim 25,wherein the act of supporting one or more wafers comprises the act ofpositioning the wafers substantially parallel to the rows.
 30. Themethod of claim 25, wherein the act of supporting one or more waferscomprises the act of positioning at least one of the wafers between apair of neighboring rows.
 31. The method of claim 25, wherein the act ofsupporting one or more wafers comprises the act of positioning thewafers below the plate.
 32. The method of claim 25, wherein the act ofsupporting one or more wafers comprises the act of positioning thewafers above the plate.
 33. A method of diffusing fluid through a wetsemiconductor processing system comprising forcing fluid through a platehaving a plurality of slots arranged in rows with a plurality of therows having at least one central slot, the central slots of at least tworows having different lengths.
 34. The method of claim 33 wherein theact of forcing fluid, forces fluid through two adjacent rows withcentral slots of different lengths.
 35. The method of claim 33, whereinthe act of forcing fluid comprises the act of generating local pressuredrops through the slots.
 36. The method of claim 33, wherein the act offorcing fluid comprises the act of forcing fluid through a plurality ofthe rows arranged in a repetitive pattern.
 37. The method of claim 33,wherein the act of forcing fluid comprises the act of forcing fluidthrough a plurality of the rows arranged in an alternating pattern. 38.The method of claim 33, wherein the act of forcing fluid comprises theact of forcing fluid through at least one row having a slot patterncomprising a longer central slot between two shorter end slots.
 39. Themethod of claim 33, wherein the act of forcing fluid comprises the actof forcing fluid through at least one row having a slot patterncomprising a shorter central slot between two longer end slots.
 40. Themethod of claim 33, wherein the act of forcing fluid comprises the actof forcing fluid through a plurality of the rows which form a patternwith rows having a shorter central slot between two longer end slotsbeing neighbored by rows having a longer central slot between twoshorter end slots.
 41. The method of claim 33, wherein the methodfurther comprises the act of controlling the temperature of the fluid.42. A method for wet processing of wafers comprising diffusingpressurized fluid through a plate having a plurality of slots arrangedin rows with a plurality of the rows having at least one end slot, theend slots of at least two rows having different lengths.
 43. The methodof claim 42, wherein the act of diffusing pressurized fluid comprisesthe act of forcing fluid through the slots.
 44. The method of claim 43,wherein the act of forcing fluid comprises the act of generating localpressure drops across the plate.
 45. The method of claim 42, wherein theact of diffusing pressurized fluid forces fluid through two adjacentrows with end slots of different lengths.
 46. The method of claim 42,wherein the act of diffusing pressurized fluid comprises the act offorcing fluid through a plurality of the slots arranged in a staggeredpattern.
 47. The method of claim 42, wherein the act of diffusingpressurized fluid comprises the act of forcing fluid through a pluralityof the rows arranged in an alternating repetitive pattern.
 48. Themethod of claim 42, wherein the act of diffusing pressurized fluidcomprises the act of forcing fluid through a plurality of the rowshaving a slot pattern comprising a longer central slot between twoshorter end slots.
 49. The method of claim 42, wherein the act ofdiffusing pressurized fluid comprises the act of forcing fluid through aplurality of the rows having a slot pattern comprising a shorter centralslot between two longer end slots.
 50. The method of claim 42, whereinthe act of diffusing pressurized fluid comprises the act of forcingfluid through a plurality of the rows having a pattern with rows havinga shorter central slot between two longer end slots being neighbored byrows having a longer central slot between two shorter end slots.
 51. Themethod of claim 42, wherein the method further comprises the act ofsupplying fluid to the plate through a manifold positioned upstream ofthe plate.
 52. The method of claim 51, wherein the method furthercomprises the act of supplying fluid to the manifold from a pumppositioned upstream of the manifold.
 53. The method of claim 52, whereinthe act of supplying fluid comprises the act of supplying fluid at aflow rate of about 20 liters/min.